Global Communication Network

ABSTRACT

A method for modifying a communication signal for transmission from a source to a destination includes identifying, by data processing hardware, a target platform for communication with a communication device. The method includes establishing a communication connection between the target platform and the communication device and identifying an available communication channel for communicating data between the target platform and the communication device. The method also includes modifying a communication signal by multiplying the communication signal with a pseudo random noise spreading code. The method also includes causing transmission of the modified communication signal from the communication device to the target platform through the available communication channel. The modified communication signal is transmitted below a thermal noise of the available communication channel.

TECHNICAL FIELD

This disclosure relates to a global communication network.

BACKGROUND

A communication network is a large distributed system for receivinginformation (signal) and transmitting the information to a destination.Over the past few decades the demand for communication access hasdramatically increased. Although conventional wire and fiber landlines,cellular networks, and geostationary satellite systems have continuouslybeen increasing to accommodate the growth in demand, the existingcommunication infrastructure is still not large enough to accommodatethe increase in demand. In addition, some areas of the world are notconnected to a communication network and therefore cannot be part of theglobal community where everything is connected to the internet.

Satellites are used to provide communication services to areas wherewired cables cannot reach. Satellites may be geostationary ornon-geostationary. Geostationary satellites remain permanently in thesame area of the sky as viewed from a specific location on earth,because the satellite is orbiting the equator with an orbital period ofexactly one day. Non-geostationary satellites typically operate in low-or mid-earth orbit, and do not remain stationary relative to a fixedpoint on earth; the orbital path of a satellite can be described in partby the plane intersecting the center of the earth and containing theorbit. In addition, the communication devices significantly increase thecost of building, launching and operating each satellite; they alsogreatly complicate the design and development of the satellitecommunication system and associated antennas and mechanisms to alloweach satellite to acquire and track other satellites whose relativeposition is changing. Each antenna has a mechanical or electronicsteering mechanism, which adds weight, cost, vibration, and complexityto the satellite, and increases risk of failure. Requirements for suchtracking mechanisms are much more challenging for inter-satellite linksdesigned to communicate with satellites in different planes than forlinks, which only communicate with nearby satellites in the same plane,since there is much less variation in relative position. Similarconsiderations and added cost apply to high-altitude communicationballoon systems with inter-balloon links.

SUMMARY

One aspect of the disclosure provides a method for modifying acommunication signal for transmission from a source to a destination.The method includes identifying, by data processing hardware, a targetplatform for communication with a communication device, establishing acommunication connection between the target platform and thecommunication device, and identifying an available communication channelfor communicating data between the target platform and the communicationdevice. The target platform and the communication device may each be anaerial platform (e.g., drone), a terrestrial platform (e.g., car, truck,train, etc.), or an aquatic platform (e.g., boat). The method alsoincludes modifying a communication signal by multiplying thecommunication signal with a pseudo random noise spreading code andcausing transmission of the modified communication signal from thecommunication device to the target platform through the availablecommunication channel. The modified communication signal is transmittedbelow a thermal noise of the available communication channel.

Implementations of the disclosure may include one or more of thefollowing optional features. In some implementations, the methodincludes, before modifying the communication signal, generating, by thedata processing hardware, the communication signal. The pseudo randomnoise spreading code may spread the communication signal by a factor of128. In some examples, the modified communication signal is transmittedthrough the available communication channel in a Ku band. Other bandsare possible as well.

In some implementations, identifying the target platform includestracking, by the data processing hardware, global positions of highaltitude platforms and determining, by the data processing hardware, acollection of high altitude platforms and available communicationchannels for transmitting the communication signal at a communicationtime of the transmission of the modified communication signal from thecommunication device. Identifying the target platform also includesselecting, by the data processing hardware, the target platform from thecollection of high altitude platforms.

In some examples, identifying the target platform includes querying adata source stored in memory hardware in communication with the dataprocessing. The method may also include querying of the data source fordetermining a high altitude platform for communication with thecommunication device and available communication channels fortransmitting the communication signal at a communication time of thetransmission of the modified communication signal from the communicationdevice.

The communication device may include a phased array antenna. In someexamples, establishing the communication connection between the targetplatform and the communication device includes steering one or morearray elements of the phased array antenna to move a correspondingcommunication beam. In some examples, a ground station or a source highaltitude platform includes the data processing device.

Another aspect of the disclosure provides a communication system. Thecommunication system includes a modem and a phased array antenna system.The modem is configured to receive a communication and modify thecommunication signal by multiplying the communication signal with apseudo random noise spreading code. The phased array antenna system isin communication with the modem. The phased array antenna systemincludes a phased array antenna system and data processing hardware. Thedata processing hardware is configured to perform operations. Theseoperations include identifying a target platform for communication withthe phased array antenna and establishing a communication connectionbetween the target platform and the phased array antenna. The operationsalso include identifying an available communication channel forcommunicating data between the target platform and the phased arrayantenna. The operations further include transmitting the modifiedcommunication signal from the phased array antenna to the targetplatform through the available communication channel. The modifiedcommunication signal is transmitted below a thermal noise of theavailable communication channel. The target platform and thecommunication device may each be an aerial platform (e.g., drone), aterrestrial platform (e.g., car, truck, train, etc.), or an aquaticplatform (e.g., boat).

The operations may further include, before modifying the communicationsignal, generating the communication signal. In some examples, theoperations include, before modifying the communication signal,receiving, at the data processing hardware, the communication signal.The pseudo random noise spreading code may spread the communicationsignal by a factor of 128. Other spreading modes include, but are notlimited to, spreading modes for lowering signal-to-noise ratio (SNR) toDVB-S2X (an extension of DVB-S2 satellite digital broadcasting standard)and RCS2 (for Higher Layers for Satellite (HLS) communications).

In some implementations, the modified communication signal istransmitted through the available communication channel in a Ku band.Identifying the target platform includes tracking global positions ofhigh altitude platforms and determining a collection of high altitudeplatforms and available communication channels for transmitting thecommunication signal at a communication time of the transmission of themodified communication signal from the phased array antenna. Inaddition, identifying the target platform may include selecting thetarget platform from the collection of high altitude platforms.

In some examples, identifying the target platform includes querying adata source stored in memory hardware in communication with the dataprocessing hardware for a high altitude platform for communication withthe phased array antenna and available communication channels fortransmitting the communication signal at a communication time of thetransmission of the modified communication signal from the phased arrayantenna. The phased array antenna may include antennas disposed on amicro strip and a phase shifter connected to at least one of theantennas.

Establishing the communication connection between the target platformand the phased array antenna includes steering one or more arrayelements of the phased array antenna to move a correspondingcommunication beam. In some examples, the phased array antenna system isdisposed on a ground station or a source high altitude platform.

The details of one or more implementations of the disclosure are setforth in the accompanying drawings and the description below. Otheraspects, features, and advantages will be apparent from the descriptionand drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a schematic view of an exemplary communication system.

FIG. 1B is a schematic view of an exemplary global-scale communicationsystem with satellites and high altitude platforms (HAPs), where thesatellites form a polar constellation.

FIG. 1C is a schematic view of an exemplary group of satellites of FIG.1A forming a Walker constellation.

FIGS. 2A and 2B are perspective views of example HAPs.

FIG. 3 is a perspective view of an example satellite.

FIGS. 4A and 4B are schematic views of an exemplary path between HAPsfor sending a communication between a first user and a second user in aglobal-scale communication system.

FIG. 5 is a schematic view of an exemplary arrangement of operations forcommunicating between a source and a destination.

FIG. 6 is a schematic view of an example computing device executing anysystems or methods described herein.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

A communication system may include satellites and high altitudeplatforms (HAPs). A ground station may transmit a communication to thesatellite, which in turn transmits it to the HAP. The HAP may send ortransmit the received communication to one or more user terminals. Thereverse may also occur, where the user terminal transmits acommunication to the HAP, the HAP transmits the communication to thesatellite, and the satellite relays the communication to the groundstation. Each satellite may include one or more transponders forrelaying the communication from the ground station to the HAP(s) andvice versa. A transponder has a limited number of bandwidth or channelsthat may be used for transmitting one or more communications. Satellitecommunications may include television broadcast, telephone, radio,internet, data, and military. Therefore, to transmit a fairly smallercommunication, e.g., having a significantly smaller data rate than thetransponder provides (e.g., 10 kb/second), a modem at the ground stationor the HAP, may spread the smaller signal using direct-sequence spreadspectrum (DSSS) before transmitting the communication through a phasedarray antenna (e.g., under noise threshold). Moreover, the phased arrayantenna system may select a channel of the transponder that is availablefor use, i.e., not being used, to transmit the modified spread signal.However, if the transponder does not have any available channels, thetransmitter may utilize a channel that is already transmitting a signalsince the modified spread signal does not interfere with any signalsbeing transmitted through the transponder channels.

Referring to FIGS. 1A-1C, in some implementations, a global-scalecommunication network 100 includes one or more ground stations 110, oneor more terminals 120, one or more high altitude platforms (HAPs) 200,and one or more satellites 300. Each ground station 110 may communicatewith the one or more satellites 300, each satellite 300 may communicatewith the one or more HAPs 200, and each HAP 200 may communicate with theone or more terminals 120, 120 a, 120 b. The ground stations 110 may beconnected to one or more service providers (not shown) and the terminals120 may be a user terminal (e.g., mobile devices, residential WiFidevices, home networks, etc.). The ground station 110 may be astationary platform, an aerial platform (e.g., drone), a terrestrialplatform (e.g., car, truck, train, etc.), or an aquatic platform (e.g.,boat).

In some implementations, a HAP 200 is an aerial communication devicethat operates at high altitudes (e.g., 17-22 km). The HAP 200 may bereleased into the earth's atmosphere, e.g., by an air craft, or flown tothe desired height. Moreover, the HAP 200 may operate as aquasi-stationary aircraft. In some examples, the HAP 200 is an aircraft200 a, such as an unmanned aerial vehicle (UAV); while in otherexamples, the HAP 200 is a communication balloon 200 b. The satellite300 may be in Low Earth Orbit (LEO), Medium Earth Orbit (MEO), or HighEarth Orbit (HEO), including Geosynchronous Earth Orbit (GEO).

The HAPs 200 may move about the earth 5 along a path, trajectory, ororbit 202 (also referred to as a plane, since their orbit or trajectorymay approximately form a geometric plane). Moreover, several HAPs 200may operate within the same or different orbits 202. For example, someHAPs 200 may move approximately along a latitude of the earth 5 (or in atrajectory determined in part by prevailing winds) in a first orbit 202a, while other HAPs 200 may move along a different latitude ortrajectory in a second orbit 202 b. The HAPs 200 may be grouped amongstseveral different orbits 202 about the earth 5 and/or they may movealong other paths 202 (e.g., individual paths). Similarly, thesatellites 300 may move along different orbits 302, 302 a-n. Multiplesatellites 300 working in concert form a satellite constellation. Thesatellites 300 within the satellite constellation may operate in acoordinated fashion to overlap in ground coverage. In the example shownin FIG. 1B, the satellites 300 operate in a polar constellation byhaving the satellites 300 orbit the poles of the earth 5; whereas, inthe example shown in FIG. 1C, the satellites 300 operate in a Walkerconstellation, which covers areas below certain latitudes and provides alarger number of satellites 300 simultaneously in view of a groundstation 110 on the ground (leading to higher availability, fewer droppedconnections). In some examples, satellites 300 in GEO orbit within aplane of the Earth's equator have a radius of approximately 42,164 km or26,199 miles measured from the center of the earth 5.

When building a global communication system 100, one of the difficultiesto be considered is creating links 22 that allows a ground station 110in the U.S. to communicate with a user terminal 120 in Japan, forexample. If the global communication system 100 includes HAPs 200, thenthe ground station 110 in the U.S. may not have a direct line-of-sightwith the HAP 200 that transmits the communication 20 to the userterminal 120 in Japan. One way to achieve a link 22 from a groundstation 110 that does not have a direct line-of-sight (e.g., a link 22)with a HAP 200 is to use a satellite 300 that is in the line-of-sight ofboth the ground station 110 and the HAP 200. Thus, the ground station110 can transmit the communication 20 to the destination terminal 120,e.g., Japan using the satellite 300. The use of the satellite 300requires buying or leasing bandwidth of a transponder 312 from asatellite service provider.

In some examples, the transponder 312 of a satellite gathers signals 20from transmitters, e.g., one or more ground stations 110 or one or moreuser terminals 120, over a set of uplink frequencies and re-transmitsthe signals 20 on a different set of downlink frequencies to receivers,e.g., one or more ground stations 110 or one or more user terminals 120on earth 5, without changing the content of the signal(s) 20. In someexamples, a transponder 312 is defined by a set of satellite equipmentthat defines one unit of satellite capacity, usually 24 MHz or 36 MHz.Therefore, each transponder 312 of a satellite provides limitedbandwidth that is divided among communication service providers (e.g.,TV broadcasters, or Virtual Network Operators (VSATs), or governmentorganizations). Communication service providers may lease one or moretransponders 312 of one or more satellites 300 from the satelliteservice provider to broadcast their communication 20. Leasing atransponder 312 may be extremely costly due to the limited number oftransponders 312 available on each satellite 300. When building a globalcommunication network 100, the most costly consideration can be thebandwidth (i.e., channels). Due to that, the service may be extremelyexpensive, since there may be a limited number of channels or bandwidththat may be used. Therefore, it may be desirable to build acommunication network 100 that allows for a communication serviceprovider to transmit and receive a communication 20 using the satellites300, while maintaining a low cost of leasing bandwidth from thesatellite service providers. Direct Sequence Spread Spectrum (DSSS) maybe implemented as part of the global communication network 100 (e.g.,modem 112) to reduce cost, power density, and secure communication,while transmitting a signal 20 globally or locally from the groundstation 110 to user terminals 120 by way of the satellite 300 and/orHAPs 200. The use of DSSS allows the communication service provider totransmit a signal 20 below noise level without interfering with othersignal transmissions, i.e., the transmitted signals 20 may co-exist withother signals being transmitted above the noise level. This allows for aglobal communication network 100, which increases the bandwidth bysending signals or communication 20 within the noise levels, which isnormally not used for communications, resulting in low operational costof the global communication network 100.

In some implementations, the ground station 110 is a terrestrial radiostation configured to provide extra planetary telecommunication with theone or more satellites 300. In other implementations, the ground station110 is moving across land, air, or water. A ground station 110 incommunication with a satellite 300 establishes a link 22. In someexamples, if a ground station 110 is trying to establish a link 22 witha satellite 300 that is moving with respect to the ground station 110,or the ground station 110 is moving with respect to the satellite 300,or both are moving with respect to one another, then the ground station110 includes a phased array antenna system 116 (e.g., tracking antenna)to maintain the link 22 with the satellite 300. In other examples, whenthe ground station 110 is in communication with a satellite 300 having afixed position with respect to the ground station 110, then the groundstation 110 includes a phase array antenna 117 that always points to thesame direction, i.e., the direction of the satellite 300 to maintain acommunication link 22.

The ground station 110 may be stationary or mobile (e.g., on a boat or amoving object). In some examples, the ground station 110 includes a dataprocessing device, such as a modem 112, 112 g that processes a receivedcommunication 20 before sending it to the satellite 300, or processes areceived communication 20 from the satellite 300.

Direct-sequence spread spectrum (DSSS) is a spread spectrum modulationtechnique used in telecommunications. Spread spectrum systems areconfigured to transmit a modified signal S3 (FIGS. 4A and 4B) thatcontains the communication 20 using a bandwidth that is in excess of thebandwidth that the message signal S1 actually needs, which results in awideband signal that appears as a noise signal allowing greaterresistance to intentional and unintentional interference with thetransmitted modified signal S3. Therefore, a phased array antenna system116 (at the ground station 110 or HAP 200) transmits a modified signalS3, 20 below the thermal noise after receiving a data signal S1, wherethe modified signal S3 is transmitted below the thermal noise level ofthe bandwidth. When sending a modified signal S3, the modem 112, 112 gmultiples a data signal S1 with a unique series S2 producing a noisesignal, i.e., the modified signal S3. When receiving the modified signalS3, the modem 112, 112 g at the receiving end regenerates the datasignal S1 by multiplying the modified signal S3 with the same uniqueseries S2.

DSSS phase-shifts a signal wave pseudo randomly with a continuous stringof pseudo-noise code symbols called chips; each chip has a much shorterduration than an information bit. In other words, each information bitof the data signal S1 is modulated by a sequence S2 of much fasterchips. Thus, the chip rate is much higher than the information signalbit rate. Moreover, DSSS uses a signal structure where the sequence ofchips produced by the transmitter (i.e., ground station 110 or HAP 200)is known by the receiving end (i.e., ground station 110 or HAP 200).This allows for the receiving end to use the same pseudo-noise sequenceS2 to counteract the effect of the pseudo-noise sequence S2 on thereceived modified signal S3 in order to reconstruct the informationsignal S2.

In some implementations, the modem 112, 112 g of the ground station 110is a DSSS modem. The modem 112, 112 g (modulator-demodulator) is adevice that modulates signals to encode digital information anddemodulates signals to decode the transmitted information. The modem112, 112 g produces a signal that is easily transmitted and decoded toreproduce the original data. The modem 112, 112 g receives acommunication signal S1 from a communication service provider andgenerates a modified signal S3 or a communication 20 to transmit. Themodem 112, 112 g selects a narrow band channel and spreads thecommunication signal S1 by multiplying it with a pseudo random noisespreading code S2. For example, the DSSS modem 112, 112 g receives thecommunication signal S1 and converts it to a modified signal S3 bymultiplying the data signal S1 with a PN sequence S2 (pseudo-randomnoise spreading code), which is independent of the data signal S1; thusproducing the modified signal S3 for transmission. In some examples, thePN sequence spreads the information signal S by a factor of 128, butthere is no limit on the amount of spreading. The pseudo-random noisespreading code S2 can be implemented as forward error correction (FEC)coding, repetition coding, frequency hopping, and/or adaptive spreading.Other techniques are possible as well. Other spreading modes include,but are not limited to, spreading modes for lowering signal-to-noiseratio (SNR) to DVB-S2X (an extension of DVB-S2 satellite digitalbroadcasting standard) and RCS2 (for Higher Layers for Satellite (HLS)communications).

In order to retrieve the original data signal S1, a receiver modem(e.g., on a HAP 200) de-spreads the transmitted modified signal S3,i.e., multiplies the transmitted modified signal S3 with the same PNsequence S2. If a different PN sequence is used, then the modem 112, 112g at the receiving end fails to de-spread or retrieve the original datasignal S1. Similarly, when the DSSS modem 112, 112 g receives a modifiedsignal S3, the DSSS modem 112, 112 g multiplies the received modifiedsignal S3 with the PN sequence S2 used at the transmitting modem. Inother words, when the DSSS modem 112, 112 g receives an informationsignal S1, it spreads the information signal S1 resulting in a modifiedsignal S3; and when the DSSS modem 112, 112 g receives a modified signalS3, the DSSS modem 112, 112 g de-spreads the modified signal S3resulting in an information signal S1. When the modem 112, 112 g spreadsthe information signal S1, its energy is spread over a wide set offrequencies/channels, where each frequency/channel has a portion of thatenergy. The DSSS modem 112, 112 g spreads a bandwidth BW_(S1) of theinformation signal S1 over a much larger bandwidth BW_(SS), whereBW_(SS)>>BW_(S1). The SS signal spectrum is white noise-like. Theamplitude and the power of the SS-signal is the same as the informationsignal S1.

Zero-mean White Gaussian Noise (WGN) has the same power spectral densityfor all frequencies. ‘White’ is used because white light contains equalamounts of all frequencies within the visible band of electromagneticradiation. Pseudo-Random Noise (PN) code sequence acts like anoise-like, yet deterministic carrier used to spread the energy of asignal over a bandwidth (e.g., the bandwidth of the transponder 312).Selection of a good PN code S2 is important since the length and type ofthe code sets the bounds of the capability of the modem 112, 112 g. Insome examples, the PN code S2 is a Pseudo-Noise or Pseudo-Randomsequence of 1's and 0's. However, the PN code is not a real randomsequence because it is periodic. Random signals cannot be predicted.Therefore, the transmitted modified signal S3 is secure, has low powerbecause it is spread over the channels of the transponder, and capableof being transmitted to any global terminal since the communicationsystem is using existing equipment 110, 200, 300.

As previously discussed, the satellites 300 may be geosynchronoussatellite, meaning that the satellite 300 returns to the same locationover the earth 5 every day, or geostationary satellite, which means thatthe satellite 300 appears to be at a fixed location in the sky from anobserver on earth 5. When the ground station 110 is in communicationwith a geosynchronous satellite, the phased array antenna system 116,116 g of the ground station 110 may include a tracking device 114, 114 gfor tracking the moving satellites 300 orbiting the earth 5 that arewithin the ground station's field of view. The tracking device 114, 114g may be part of or separate from the phased array antenna system 116,116 g of the ground station 110, where the phased array antenna system116, 116 g is designed to communicate with one or more satellites 300.

In some implementations, the phased array antenna system 116, 116 gincludes a wideband active phased array antenna 117, 117 g and dataprocessing hardware 118, 118 g. Phased array antenna systems 116, 116 gprovide fast beam steering, which is the ability to generatesimultaneous beams and dynamically adjust the characteristics of thebeam patterns. The phased array antenna 117, 117 g includes a set ofindividual antennas that transmit and/or receives radio waves. Theindividual antennas are connected together in such a way that theindividual current of each antenna has specific amplitude and phaserelationship, allowing the individual antennas to act as a singleantenna. The relative phases of the respective signals feeding theantennas of the phased array antenna are set in a manner that aneffective radiation pattern of the array is reinforced in a desireddirection and suppressed in undesired directions. The phaserelationships between the individual antennas may be fixed (e.g., atower array antenna), or adjustable (e.g., beam steering antenna). Insome examples, the phased array antenna 117, 117 g includes antennasdisposed on a micro strip and a phase shifter connected to at least oneof the antennas. Moreover, the wideband active phased array antenna 117,117 g allows the transmission of the message bandwidth, whichsignificantly exceeds the coherence bandwidth of the channel, i.e.,allowing the global communication network 100 to transmit below thethermal noise level. In some examples, active phased array antennas 117,117 g incorporate transmit amplification with phase shift in eachantenna element or group of elements.

The data processing hardware 118, 118 g of the phased array antennasystem 116, 116 g may include the tracking device 114, 114 g or may bein communication with the tracking device 114, 114 g. The dataprocessing hardware 118, 118 g of the phased array antenna system 116,116 g is configured to identify a target HAP 200 or satellite 300 forcommunication with the phased array antenna 117, 117 g (e.g., having aline-of-sight with the phased array antenna 117, 117 g) and establish acommunication connection or link 22 between the target HAP 200 orsatellite 300 and the ground station 110. Moreover, the data processinghardware 118, 118 g of the phased array antenna system 116, 116 g isconfigured to identify an available communication channel forcommunicating data between the target HAP 200 or satellite 300 and theground station 110. Moreover, the data processing hardware 118, 118 g ofthe phased array antenna system 116, 116 g is configured to transmit amodified communication signal (received from the modem 112, 112 g) fromthe phased array antenna 117, 117 g to the target HAP 200 or satellite300 through the available communication channel or link 22. The modifiedcommunication signal S3 is transmitted below a thermal noise of theavailable communication channel. The data processing hardware 118, 118 gof the phased array antenna system 116, 116 g identifies the target HAP200 or satellite 300 by tracking global positions of HAPs 200 orsatellites 300 and determining a collection of HAPs 200 or satellites300 for communication with the phased array antenna 117, 117 g andavailable communication channels for transmitting the modified signal S3at a communication time of the transmission of the modified signal S3from the phased array antenna 117, 117 g, and selects the target HAP 200or satellite 300 from the collection of HAPs 200 or satellites 300.Alternatively, identifying the target HAP 200 or satellite 300 mayinclude querying a data source (not shown) stored in memory hardware incommunication with data processing hardware 118, 118 g in communicationwith the data processing hardware of the target HAP 200 or satellite 300that, for example, has or does not have a line-of-sight with the phasedarray antenna 117, 117 g and available communication channels fortransmitting the modified signal S3 at a communication time of thetransmission of the modifies communication S3 from the phased arrayantenna S3.

Referring to FIGS. 2A and 2B, in some implementations, the HAP 200, 200a, 200 b includes an antenna 210, 210 a, 210 b that receives/transmits acommunication 20 from a user terminal 120. The HAP 200, 200 a, 200 balso includes the phased array antenna system 116, 116 a, 116 b and themodem 112, 112 a, 112 b, similar to the phased array antenna system 116g and the modem 112 g discussed with respect to the ground station 110.The phased array antenna system 116, 116 a, 116 b allows forcommunication between the HAP 200 and the satellite 300. Thus the arrayantenna system 116 a,116 b includes the tracking device 114 a, 114 b,the phased array antenna 117,117 a, 117 b, and the data processinghardware 118, 118 a, 118 b same as the data processing hardware 118 g ofthe ground station. In some examples, and as previously discussed, thesatellite 300 and/or the HAP 200 is moving; therefore, the phased arrayantenna system 116, 116 a, 116 b of the HAP 200 needs to track aposition of one or more satellites 300 to maintain a communication link22 between the HAP 200 and the satellite 300. The satellite 300 receivesa communication from one of the phased array antenna system 116, 116 a.116 b, 116 g of the ground station 110 or the HAP 200 and sends it backto the other one of the phased array antenna system 116, 116 a, 116 b,116 g of the ground station 110 or the HAP 200. The HAP 200 may includea data processing device 220 that processes the received communication20 (i.e., the modified signal S3 or the signal received from thecommunication provider or user terminals) and determines a path of thecommunication 20 to arrive at the destination terminal 120 (e.g., userterminal). The processing device 220 may include the modem 112, 112 a,220 b. In some implementations, user terminals 120 on the ground havespecialized antennas that send/receive communication signals to/from theHAPs 200. The HAP 200 receiving the communication 20 from the userterminal 120 sends the communication 20 to one or more satellites 300.The HAP 200 also includes an antenna 210 for receiving and sending thecommunications 20 to the user terminals 120.

FIG. 2A illustrates an example aircraft 200 a, such as an unmannedaerial vehicle (UAV). A UAV, also known as a drone, is an aircraftwithout a human pilot onboard. There are two types of UAVs, autonomousaircrafts and remotely piloted aircraft. As the name suggests,autonomous aircrafts are designed to autonomously fly, while remotelypiloted aircrafts are in communication with a pilot who pilots theaircraft. In some examples, the aircraft 200 a may be remotely pilotedand autonomous at the same time. The UAV usually includes wings tomaintain stability, a GPS system to guide it through its autonomouspiloting, and a power source (e.g., internal combustion engine orelectric battery) to maintain long hours of flight. In some examples,the UAV is designed to maximize efficiency and reduce drag duringflight. Other UAV designs may be used as well.

FIG. 2B illustrates an example communication balloon 200 b that includesa balloon 204 (e.g., sized about 49 feet in width and 39 feet in heightand filled with helium or hydrogen), an equipment box 206, and solarpanels 208. The equipment box 206 includes a data processing device 220that executes algorithms to determine where the high-altitude balloon200 a needs to go, then each high-altitude balloon 200 b moves into alayer of wind blowing in a direction that may take it where it should begoing. The equipment box 206 also includes batteries to store power anda transceiver (e.g., antennas 210) to communicate with other devices(e.g., other HAPs 200, satellites 300, ground stations 110, such as userterminals 110 b, internet antennas on the ground, etc.). The solarpanels 208 may power the equipment box 206.

Communication balloons 200 b are typically released in to the earth'sstratosphere to attain an altitude between 11 to 23 miles and provideconnectivity for a ground area of 25 miles in diameter at speedscomparable to terrestrial wireless data services (such as, 3G or 4G).The communication balloons 200 b float in the stratosphere, at analtitude twice as high as airplanes and the weather (e.g., 20 km abovethe earth's surface). The high-altitude balloons 200 a are carriedaround the earth 5 by winds and can be steered by rising or descendingto an altitude with winds moving in the desired direction. Winds in thestratosphere are usually steady and move slowly at about 5 and 20 mph,and each layer of wind varies in direction and magnitude.

Referring to FIG. 3, a satellite 300 is an object placed into orbit 302around the earth 5 and may serve different purposes, such as military orcivilian observation satellites, communication satellites, navigationssatellites, weather satellites, and research satellites. The orbit 302of the satellite 300 varies depending in part on the purpose of thesatellite 200 b. Satellite orbits 302 may be classified based on theiraltitude from the surface of the earth 30 as Low Earth Orbit (LEO),Medium Earth Orbit (MEO), and High Earth Orbit (HEO). LEO is ageocentric orbit (i.e., orbiting around the earth 5) that ranges inaltitude from 0 to 1,240 miles. MEO is also a geocentric orbit thatranges in altitude from 1,200 mile to 22.236 miles. HEO is also ageocentric orbit and has an altitude above 22,236 miles. GeosynchronousEarth Orbit (GEO) is a special case of HEO. Geostationary Earth Orbit(GSO, although sometimes also called GEO) is a special case ofGeosynchronous Earth Orbit. Satellites 300 placed in the GEO orbit can“stand still” with respect to a certain location on earth 5. Thus, aperson on earth 5 looking at a satellite 300 in the GEO orbit wouldperceive that the satellite 300 is not moving. Therefore, the satellites300 in GEO orbit maintain a position with respect to a location on earth5. Thus, an antenna 116 of a ground station 110 communicating with asatellite 300 in the GEO orbit does not need to keep tracking thesatellite 300 as it moves, it only needs to point to a direction of thesatellite 300 in its stationary position with respect to the groundstations 110.

In some implementations, a satellite 300 includes a satellite body 304having a payload that includes a data processing device 310, e.g.,similar to the data processing device 220 of the HAPs 200. The dataprocessing device 310 executes algorithms to determine where thesatellite 300 is heading. The satellite 300 also includes an antenna 320for receiving and transmitting a communication 20. The satellite 300includes solar panels 308 mounted on the satellite body 204 forproviding power to the satellite 300. In some examples, the satellite300 includes rechargeable batteries used when sunlight is not reachingand charging the solar panels 308.

In some examples, the payload of each satellite 300 includes one or moretransponder(s) 312. Each transponder 312 receives a communication 20from a ground station 110, processes, encodes, amplifies andrebroadcasts the signal over a large area of the surface of the earth 5to one or more terminals 120. Therefore, the transponder 312 is a signalprocessing unit that uses a signal high-power amplification chain. Eachtransponder 312 handles a particular frequency range (i.e., bandwidth orchannels) centered on a specific frequency. In some examples, eachsatellite 300 includes at least one transponder 312 (e.g., 60transponders or more, each transponder 312 capable of transmitting up to10 digital television signals), each transponder 312 capable ofsupporting one or more communication channels.

The transponder 312 may be used for broadcasting television channels. Insome examples, the communication 20 received at the user terminal 120from the transponder 312 is encoded so that only paying customers at theuser terminals 120 are capable of receiving the communication 20. Insome examples, one or more satellite service providers own thetransponders 312 and lease bandwidth or channels of a transponder 312 toa communication service provider. The communication service providerwants to transmit/receive a communication 20 at the ground station 110to/from user terminals 120.

In some examples, the transponder 312 gathers signals 20 from one ormore ground stations 110 over a set of uplink frequencies andre-transmits the signals 20 on a different set of downlink frequenciesto receivers on earth 5, without changing the content of the signal(s)20. In some examples, a transponder 312 is defined by a set of satelliteequipment that defines one unit of satellite capacity, usually 24 MHz or36 MHz. Therefore, each transponder 312 of a satellite 300 provideslimited bandwidth that is divided among communication service providers(e.g., TV broadcasters, or Virtual Network Operators (VSATs), orgovernment organizations). Communication service providers may lease oneor more transponders 312 of one or more satellites 300 from thesatellite service provider to broadcast their communication 20. Leasinga transponder 312 may be extremely costly due to the limited number oftransponders 312 available on each satellite 300. When building a globalcommunication network, the most costly consideration to be made is thebandwidth (i.e., channels). Due to that, the service may be extremelyexpensive since there is a limited number of channels or bandwidth thatmay be used. Therefore, it is desirable to build a communication network100 that allows for a communication service provider to transmit andreceive a communication 20 using the satellites 300, while maintaininglow cost of leasing bandwidth from the satellite service providers.Therefore, a direct spectrum modem 112 is used at the ground station 110and the HAP 200 to reduce cost, power density, and secure communication,while transmitting a signal 20 globally or locally from/ground station110 to user terminals 120 by way of the satellite 300 and HAPs 200.

In some implementations, the satellite 300 includes tracking, telemetry,command and ranging (TT&R) that provides a connection between thesatellite 300 and facilities on the ground, e.g., the ground station 110or the HAPs. The TT&R ensures that the satellite 300 establishescommunication or a link 22 to successfully receive/transmit acommunication 20. The TT&R performs several operations, including, butnot limited to, monitoring the health and status of the satellite 300 byway of collecting, processing, and transmitting data from the one source(e.g., the ground station 110) to the destination (e.g., HAP 200) orvice versa, passing through the satellite 300. Another operationincludes determining the satellite's exact location by way of receiving,processing, and transmitting of communications 20. Yet another operationof the TT&R includes properly controlling the satellite 300 through thereceiving, processing, and implementing of commands transmitted from theground stations 110. In some examples, a ground operator controls thesatellite 300; however, such an intervention by the operator is onlyminimal or in case of an emergency and the satellite 300 is mostlyautonomous.

In some examples, the satellite 300 includes batteries to operate thesatellite 300 when the solar panels 208 of the satellite 300 are hiddenfrom the sun due to the earth 5, the moon, or any other objects. In someexamples, the satellite 300 also includes a reaction control system(RCS) that uses thrusters to adjust the altitude and translation of thesatellite 300 making sure that the satellite 300 stays in its orbit 202.The RCS may provide small amounts of thrusts in one or more directionsand torque to allow control of the rotation of the satellite 300 (i.e.,roll, pitch, and yaw).

Referring back to FIG. 1A, in some implementations, when constructing aglobal-scale communications network 100 using HAPs and satellites 300, a‘bent pipe’ architecture is used. The bent pipe architecture, shown inFIG. 1A, is where the satellite 300 receives a communication 20 from theground station 110 and sends it to the user terminal 120, in this casethrough the HAP 200. Another example is where the satellite 300 receivesa communication 20 from the terminal 120 through the HAP 200 and sendsit to the ground station 110. The satellite 300 receives thecommunication 20 and sends it to its destination, acting like a bentpipe. In this case, the satellite 300 acts as a repeater and nosatellite 300 to satellite 300 communication occurs, i.e., the satellite300 does not transfer the communication 20 to another satellite 300before transmitting it to its destination.

Referring back to FIG. 1B, in some implementations, it is sometimesdesirable to route traffic over long distances through the globalcommunication network 100 by linking HAPs 200 to satellites 300 and/orone HAP 200 to another. For example, two satellites 300 may communicatevia inter-device links and two HAPs 200 may communicate via inter-devicelinks. Inter-device link (IDL) eliminates or reduces the number of HAP200 or satellite 300 ground station 110 hops, which decreases thelatency and increases the overall network capabilities. Inter-devicelinks allow for communication traffic from one HAP 200 or satellite 300covering a particular region to be seamlessly handed over to another HAP200 or satellite 300 covering the same region, where a first HAP 200 orsatellite 300 is leaving the first area and a second HAP 200 orsatellite 300 is entering the area. Such inter-device linking is usefulto provide communication services to areas far from the ground stations110 and the terminals 120 and may also reduce latency and enhancesecurity (fiber optic cables 12 may be intercepted and data goingthrough the cable may be retrieved). Therefore, when using IDL, thefirst device in the transmission chain (e.g., modulates thecommunication signal S1, i.e., multiplies it by the sequence S2), andthe last device in the transmission chain (e.g., HAP 200 that receivesthe modified signal S3) de-spreads the modified signal S3 beforetransmitting the communication data S1 to the user terminals 120.

The use of the IDL model is different than the “bent-pipe” model, inwhich all signal traffic goes from a source ground station 110 to asatellite 300, and then directly down to a destination, e.g., userterminal 120 or vice versa. The “bent-pipe” model does not include anyinter-device communications. Instead, the satellite 300 acts as arepeater. In some examples of “bent-pipe” models, the signal received bythe satellite 300 is amplified before it is re-transmitted; however, nosignal processing occurs. In other examples of the “bent-pipe” model,part or all of the signal may be processed and decoded to allow for oneor more of routing to different beams, error correction, orquality-of-service control; however no inter-device communicationoccurs.

In some implementations, large-scale communication constellations 100are described in terms of a number of orbits 202, 302, and the number ofHAPs 200 or satellites 300 per orbit 202, 302. HAPs 200 or satellites300 within the same orbit 202, 302 maintain the same position relativeto their intra-orbit HAP 200 or satellite 300 neighbors. However, theposition of a HAP 200 or a satellite 300 relative to neighbors in anadjacent orbit 202, 302 may vary over time. For example, in alarge-scale satellite constellation with near-polar orbits, satellites300 within the same orbit 202 (which corresponds roughly to a specificlatitude, at a given point in time) maintain a roughly constant positionrelative to their intra-orbit neighbors (i.e., a forward and a rearwardsatellite 300), but their position relative to neighbors in an adjacentorbit 302 varies over time. A similar concept applies to the HAPs 200;however, the HAPs 200 move about the earth 5 along a latitudinal planeand maintain roughly a constant position to a neighboring HAP 200.

One of the advantages of using a DSSS modem 112 to spread acommunication signal S1 before transmission, is that the ground station110 or the HAP 200 do not need a large antenna 117, which leads to areduction in the power consumption by the antenna 117, a reduction ofthe dimensions of the antenna 117 and weight of the payload of theground station 110 and the HAP 200, a more simplified mechanical designof the ground station 110 and the HAP 200.

As previously described, a communication service provider may leasechannels for transmitting signals via a transponder. The bandwidthavailable for leasing may be 36 Mhz or 24 Mhz. However, thecommunication service provider may only need a relatively smallerbandwidth to transmit his/her communication 20, (e.g., 10 kbs). In sucha case, leasing 36 Mhz or 24 Mhz may be very expensive since only 10 kbsare needed, thus it is wasteful to lease a transponder 312 that provides36 Mhz or 24 Mhz to only use a small fraction of the availablebandwidth. At any given time, on a satellite system 300, not all of thetransponders 312 are being used. For each transponder 312, a fraction ofits available channels may be in use at a given time. In addition, suchuse of the channels of each transponder 312 may vary at any given time.In order to save operational costs, a system that utilizes DSSS modems112 and transmits below the noise level of the channels being used, andcapable of hopping to an unused channel when necessary allows for asignal to be transmitted in the noise range along with other signalswithout causing interference between the signals.

In such a case, the communication service provider and the satelliteservice provider may agree that the communication service provider sendthe noise signal by way of the transponder 312 on the satellite, withoutleasing an entire bandwidth of the transponder 312 and only leasing theneeded bandwidth. This significantly reduces the operational cost ofsending a communication 20 that is relatively smaller than the availablebandwidth of a transponder 312, without having to lease the entirebandwidth of the transponder 312. Moreover, and to increase the chancesof preventing interference, the phased antenna system 116 may determinewhich channels are available and frequency hop the noise signal to anavailable channel, by moving the center of the noise signal to anyavailable unused channels, which further minimizes interference.

The algorithms used to determine the path of a communication 20 (e.g.,at the data processing device 220) may include a scoring function forassigning a score or weight value to each link (communication betweenthe ground station 110, the HAPs 200, and/or the satellites 300). Thesescores are considered in the algorithms used. For example, the algorithmmay try to minimize the cumulative weight of the path (i.e., sum of theweights of all the links that make up the path). In someimplementations, a system data processor considers the physical distance(and, closely related, latency) between the ground station 110, the HAPs200, and/or the satellites 300, the current link load compared to thecapacity of the link between the ground station 110, the HAPs 200,and/or the satellites 300, the health of the ground station 110, theHAPs 200, and/or the satellites 300, or its operational status (activeor inactive, where active indicates that the device is operational andhealthy and inactive where the device is not operational); the batteryof the ground station 110, the HAPs 200, and/or the satellites 300(e.g., how long will the device have power); and the signal strength atthe user terminal (for user terminal-to-satellite link).

FIGS. 4A-5, illustrate an arrangement of operations for communicatingbetween a source and a destination. FIG. 4A shows a source as the groundstation 110 and the destination being the user terminal 120, where thecommunication 20 travels from the ground station 110 to the satellite300 to the HAP 200, and finally to the user terminal 120. FIG. 4B showsthe same elements of FIG. 4A; however, in FIG. 4B the source of thecommunication 20 is the user terminal 120, which travels to the HAP 200,then the satellite 300, before reaching the destination ground station110. In some examples, the communication 20 of FIGS. 4A and 4B occursimultaneously, since both the ground station 110 and the HAP 200include a modem 112 that applies a pseudo-random code S2, and an antennasystem 116 that includes a phased array antenna 117 and data processinghardware 118. In some examples, data processing hardware 118 also refersto the tracking device 114 or the modem 112. The pseudo-random code S2can be implemented as forward error correction (FEC) coding, repetitioncoding, frequency hopping, and/or adaptive spreading. Other techniquesare possible as well.

FIG. 5 illustrates a method 500 for modifying a communication signal S1for transmission from a source (e.g., ground station 110 or HAP 200) toa destination (e.g., ground station 110 or HAP 200). At block 502, themethod 500 includes identifying, by the data processing hardware 118, atarget platform (e.g., the target satellite 300 or the HAP 200) forcommunication with a communication device (e.g., phased array antenna117 of the ground station 110 or the HAP 200). In some examples, thetarget platform has a line-of-sight with the communication device; whilein other examples, the target platform does not have a line-of-sightwith the communication device. In some examples, the communicationnetwork 100 only includes ground stations and HAPs 200, therefore, theHAP 200 may act as a satellite 300, and relay the communication 20 toanother destination or another HAP 200. The method 500, at block 504,includes establishing a communication connection between the targetsatellite 300 (or HAP 200) and the communication device 117 and at block506, identifying an available communication channel for communicatingdata (i.e., a modified signal S3) between the target satellite 300 (orHAP 200) and the communication device 117. The method 500 also includes,at block 508, modifying a communication signal S1 by multiplying thecommunication signal S1 with a pseudo random noise spreading code S2resulting in a modified signal S3. The method 500 also includes, atblock 510, causing transmission of the modified communication signal S3from the communication device 117 to the target satellite 300 (or HAP200) through the available communication channel. The modifiedcommunication signal S3 may be transmitted below a thermal noise of theavailable communication channel, in some examples. In other examples,the modified communication signal S3 is transmitted at, near, or abovethe thermal noise of the available communication channel.

In some implementations, the method 500 further includes, beforemodifying the communication signal S1 generating, by the modem 112, thecommunication signal S1 after receiving data from a communicationservice provider. The pseudo random noise spreading code S2 may spreadthe communication signal S1 by a factor of 128. In some examples, themodified communication signal S3 is transmitted through the availablecommunication channel in a Ku band. The Ku band is the 12-18 GHz portionof the electromagnetic spectrum in the microwave range of frequencies.The Ku band is primarily used for satellite communication, mostly fixedand broadcast services. Other bands are possible as well.

In some implementations, identifying the target satellite 300 (or HAP200), at block 502, includes tracking, by the data processing hardware(e.g., a tracking device 114), global positions of satellites 300 (orHAPs 200), and determining, by the data processing hardware (e.g.,antenna system 116), a collection of satellites 300 (or HAPs 200) forcommunication with the phased array antenna 117 and availablecommunication channels for transmitting the communication signal S1after modifying it to the modified signal S3, at a communication time ofthe transmission of the modified communication signal S3 from thecommunication device (i.e., ground station 110 or HAP 200). Identifyingthe target satellite 300, at block 502, may also include selecting, bythe data processing hardware (e.g., the antenna system 116), the targetsatellite 300 (or HAP 200) from the collection of satellites 300 (orHAPs 200).

In some examples, identifying the target satellite 300 includes queryinga data source stored in memory hardware in communication with the dataprocessing hardware, i.e., the antenna system 116 and querying of thedata source for determining a high altitude platform 200, 300 forcommunication with the communication device 110, 200 (e.g., for a highaltitude platform 200, 300 that has a line-of-sight with thecommunication device 110, 200) and available communication channels fortransmitting the communication signal, i.e., the modified signal S3, ata communication time of the transmission of the modified communicationsignal S3 from the communication device 110, 200.

In some examples, establishing the communication connection between thetarget satellite 300 and the communication device 110, 200 includessteering one or more array elements of the phased array antenna 117 tomove a corresponding communication beam. In some examples, a groundstation 110 or a source high altitude platform 200 includes the dataprocessing device 114, 118.

FIG. 6 is a schematic view of an example computing device 600 that maybe used to implement the systems and methods described in this document.The computing device 600 is intended to represent various forms ofdigital computers, such as laptops, desktops, workstations, personaldigital assistants, servers, blade servers, mainframes, and otherappropriate computers. The components shown here, their connections andrelationships, and their functions, are meant to be exemplary only, andare not meant to limit implementations of the inventions describedand/or claimed in this document.

The computing device 600 includes a processor 610, memory 620, a storagedevice 630, a high-speed interface/controller 640 connecting to thememory 620 and high-speed expansion ports 650, and a low speedinterface/controller 660 connecting to low speed bus 670 and storagedevice 630. Each of the components 610, 620, 630, 640, 650, and 660, areinterconnected using various busses, and may be mounted on a commonmotherboard or in other manners as appropriate. The processor 610 canprocess instructions for execution within the computing device 500,including instructions stored in the memory 620 or on the storage device630 to display graphical information for a graphical user interface(GUI) on an external input/output device, such as display 680 coupled tohigh speed interface 640. In other implementations, multiple processorsand/or multiple buses may be used, as appropriate, along with multiplememories and types of memory. Also, multiple computing devices 600 maybe connected, with each device providing portions of the necessaryoperations (e.g., as a server bank, a group of blade servers, or amulti-processor system).

The memory 620 stores information non-transitorily within the computingdevice 600. The memory 620 may be a computer-readable medium, a volatilememory unit(s), or non-volatile memory unit(s). The non-transitorymemory 620 may be physical devices used to store programs (e.g.,sequences of instructions) or data (e.g., program state information) ona temporary or permanent basis for use by the computing device 600.Examples of non-volatile memory include, but are not limited to, flashmemory and read-only memory (ROM)/programmable read-only memory(PROM)/erasable programmable read-only memory (EPROM)/electronicallyerasable programmable read-only memory (EEPROM) (e.g., typically usedfor firmware, such as boot programs). Examples of volatile memoryinclude, but are not limited to, random access memory (RAM), dynamicrandom access memory (DRAM), static random access memory (SRAM), phasechange memory (PCM) as well as disks or tapes.

The storage device 630 is capable of providing mass storage for thecomputing device 600. In some implementations, the storage device 630 isa computer-readable medium. In various different implementations, thestorage device 630 may be a floppy disk device, a hard disk device, anoptical disk device, or a tape device, a flash memory or other similarsolid state memory device, or an array of devices, including devices ina storage area network or other configurations. In additionalimplementations, a computer program product is tangibly embodied in aninformation carrier. The computer program product contains instructionsthat, when executed, perform one or more methods, such as thosedescribed above. The information carrier is a computer- ormachine-readable medium, such as the memory 620, the storage device 630,or memory on processor 610.

The high speed controller 640 manages bandwidth-intensive operations forthe computing device 600, while the low speed controller 660 manageslower bandwidth-intensive operations. Such allocation of duties isexemplary only. In some implementations, the high-speed controller 640is coupled to the memory 620, the display 680 (e.g., through a graphicsprocessor or accelerator), and to the high-speed expansion ports 650,which may accept various expansion cards (not shown). In someimplementations, the low-speed controller 660 is coupled to the storagedevice 630 and low-speed expansion port 670. The low-speed expansionport 670, which may include various communication ports (e.g., USB,Bluetooth, Ethernet, wireless Ethernet), may be coupled to one or moreinput/output devices, such as a keyboard, a pointing device, a scanner,or a networking device, such as a switch or router, e.g., through anetwork adapter.

The computing device 600 may be implemented in a number of differentforms, as shown in the figure. For example, it may be implemented as astandard server 600 a or multiple times in a group of such servers 600a, as a laptop computer 600 b, or as part of a rack server system 600 c.

Various implementations of the systems and techniques described here canbe realized in digital electronic circuitry, integrated circuitry,specially designed ASICs (application specific integrated circuits),FPGAs (field-programmable gate arrays), computer hardware, firmware,software, and/or combinations thereof. These various implementations caninclude implementation in one or more computer programs that areexecutable and/or interpretable on a programmable system including atleast one programmable processor, which may be special or generalpurpose, coupled to receive data and instructions from, and to transmitdata and instructions to, a storage system, at least one input device,and at least one output device.

These computer programs (also known as programs, software, softwareapplications or code) include machine instructions for a programmableprocessor and can be implemented in a high-level procedural and/orobject-oriented programming language, and/or in assembly/machinelanguage. As used herein, the terms “machine-readable medium” and“computer-readable medium” refer to any computer program product,apparatus and/or device (e.g., magnetic discs, optical disks, memory,Programmable Logic Devices (PLDs)) used to provide machine instructionsand/or data to a programmable processor, including a machine-readablemedium that receives machine instructions as a machine-readable signal.The term “machine-readable signal” refers to any signal used to providemachine instructions and/or data to a programmable processor.

Implementations of the subject matter and the functional operationsdescribed in this specification can be implemented in digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Moreover,subject matter described in this specification can be implemented as oneor more computer program products, i.e., one or more modules of computerprogram instructions encoded on a computer readable medium for executionby, or to control the operation of, data processing apparatus. Thecomputer readable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter affecting a machine-readable propagated signal, or a combinationof one or more of them. The terms “data processing apparatus”,“computing device” and “computing processor” encompass all apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, or multiple processors or computers.The apparatus can include, in addition to hardware, code that creates anexecution environment for the computer program in question, e.g., codethat constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, or a combination of one or moreof them. A propagated signal is an artificially generated signal, e.g.,a machine-generated electrical, optical, or electromagnetic signal thatis generated to encode information for transmission to suitable receiverapparatus.

A computer program (also known as an application, program, software,software application, script, or code) can be written in any form ofprogramming language, including compiled or interpreted languages, andit can be deployed in any form, including as a stand-alone program or asa module, component, subroutine, or other unit suitable for use in acomputing environment. A computer program does not necessarilycorrespond to a file in a file system. A program can be stored in aportion of a file that holds other programs or data (e.g., one or morescripts stored in a markup language document), in a single filededicated to the program in question, or in multiple coordinated files(e.g., files that store one or more modules, sub programs, or portionsof code). A computer program can be deployed to be executed on onecomputer or on multiple computers that are located at one site ordistributed across multiple sites and interconnected by a communicationnetwork.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform functions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application specific integrated circuit), or an ASIC specially designedto withstand the high radiation environment of space (known as“radiation hardened”, or “rad-hard”).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Moreover, a computer can be embedded inanother device, e.g., a mobile telephone, a personal digital assistant(PDA), a mobile audio player, a Global Positioning System (GPS)receiver, to name just a few. Computer readable media suitable forstoring computer program instructions and data include all forms ofnon-volatile memory, media and memory devices, including by way ofexample semiconductor memory devices, e.g., EPROM, EEPROM, and flashmemory devices; magnetic disks, e.g., internal hard disks or removabledisks; magneto optical disks; and CD ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,special purpose logic circuitry.

One or more aspects of the disclosure can be implemented in a computingsystem that includes a backend component, e.g., as a data server, orthat includes a middleware component, e.g., an application server, orthat includes a frontend component, e.g., a client computer having agraphical user interface or a Web browser through which a user caninteract with an implementation of the subject matter described in thisspecification, or any combination of one or more such backend,middleware, or frontend components. The components of the system can beinterconnected by any form or medium of digital data communication,e.g., a communication network. Examples of communication networksinclude a local area network (“LAN”) and a wide area network (“WAN”), aninter-network (e.g., the Internet), and peer-to-peer networks (e.g., adhoc peer-to-peer networks).

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other. In someimplementations, a server transmits data (e.g., an HTML page) to aclient device (e.g., for purposes of displaying data to and receivinguser input from a user interacting with the client device). Datagenerated at the client device (e.g., a result of the user interaction)can be received from the client device at the server.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the disclosure or of what maybe claimed, but rather as descriptions of features specific toparticular implementations of the disclosure. Certain features that aredescribed in this specification in the context of separateimplementations can also be implemented in combination in a singleimplementation. Conversely, various features that are described in thecontext of a single implementation can also be implemented in multipleimplementations separately or in any suitable sub-combination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multi-tasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure. Accordingly, otherimplementations are within the scope of the following claims. Forexample, the actions recited in the claims can be performed in adifferent order and still achieve desirable results.

What is claimed is:
 1. A method comprising: identifying, by dataprocessing hardware, a target platform for communication with acommunication device; establishing a communication connection betweenthe target platform and the communication device; identifying, by thedata processing hardware, an available communication channel forcommunicating data between the target platform and the communicationdevice; modifying, by the data processing hardware, a communicationsignal by multiplying the communication signal with a pseudo randomnoise spreading code; and causing, by the data processing hardware,transmission of the modified communication signal from the communicationdevice to the target platform through the available communicationchannel, the modified communication signal being transmitted below athermal noise of the available communication channel.
 2. The method ofclaim 1, further comprising, before modifying the communication signal,generating, by the data processing hardware, the communication signal.3. The method of claim 1, further comprising, before modifying thecommunication signal, receiving, at the data processing hardware, thecommunication signal.
 4. The method of claim 1, wherein the pseudorandom noise spreading code spreads the communication signal by a factorof
 128. 5. The method of claim 1, wherein the modified communicationsignal is transmitted through the available communication channel in aKu band.
 6. The method of claim 1, wherein identifying the targetplatform comprises: tracking, by the data processing hardware, globalpositions of high altitude platforms; determining, by the dataprocessing hardware, a collection of high altitude platforms andavailable communication channels for transmitting the communicationsignal at a communication time of the transmission of the modifiedcommunication signal from the communication device; and selecting, bythe data processing hardware, the target platform from the collection ofhigh altitude platforms.
 7. The method of claim 1, wherein identifyingthe target platform comprises querying a data source stored in memoryhardware in communication with the data processing hardware for a highaltitude platform for communication with the communication device andavailable communication channels for transmitting the communicationsignal at a communication time of the transmission of the modifiedcommunication signal from the communication device.
 8. The method ofclaim 1, wherein the communication device comprises a phased arrayantenna.
 9. The method of claim 8, wherein establishing thecommunication connection between the target platform and thecommunication device comprises steering one or more array elements ofthe phased array antenna to move a corresponding communication beam. 10.The method of claim 1, wherein a ground station or a source highaltitude platform comprises the data processing hardware.
 11. Acommunication system comprising: a modem configured to: receive acommunication signal; and modify the communication signal by multiplyingthe communication signal with a pseudo random noise spreading code; anda phased array antenna system in communication with the modem, thephased array antenna system comprising: a phased array antenna; and dataprocessing hardware configured to perform operations comprising:identifying a target platform for communication with the phased arrayantenna; establishing a communication connection between the targetplatform and the communication system; identifying an availablecommunication channel for communicating data between the target platformand the communication system; and transmitting the modifiedcommunication signal from the phased array antenna to the targetplatform through the available communication channel, the modifiedcommunication signal being transmitted below a thermal noise of theavailable communication channel.
 12. The communication system of claim11, wherein the operations further comprise, before modifying thecommunication signal, generating the communication signal.
 13. Thecommunication system of claim 11, wherein the operations furthercomprise, before modifying the communication signal, receiving thecommunication signal.
 14. The communication system of claim 11, whereinthe pseudo random noise spreading code spreads the communication signalby a factor of
 128. 15. The communication system of claim 11, whereinthe modified communication signal is transmitted through the availablecommunication channel in a Ku band.
 16. The communication system ofclaim 11, wherein identifying the target platform comprises: trackingglobal positions of high altitude platforms; determining a collection ofhigh altitude platforms and available communication channels fortransmitting the communication signal at a communication time of thetransmission of the modified communication signal from the phased arrayantenna; and selecting the target platform from the collection of highaltitude platforms.
 17. The communication system of claim 11, whereinidentifying the target platform comprises querying a data source storedin memory hardware in communication with the data processing hardwarefor a high altitude platform for communication with the phased arrayantenna and available communication channels for transmitting thecommunication signal at a communication time of the transmission of themodified communication signal from the phased array antenna.
 18. Thecommunication system of claim 11, wherein the phased array antennacomprises: antennas disposed on a micro strip; and a phase shifterconnected to at least one of the antennas.
 19. The communication systemof claim 11, wherein establishing the communication connection betweenthe target platform and the phased array antenna comprises steering oneor more array elements of the phased array antenna to move acorresponding communication beam.
 20. The communication system of claim11, wherein the phased array antenna system is disposed on a groundstation or a source high altitude platform.